Carpal tunnel syndrome

What is it?

Carpal tunnel syndrome occurs when the median nerve is compressed at the point where it passes through the carpal tunnel (Figure 1). The carpal tunnel is a narrow canal formed by the wrist bones and ligaments at the base of the palm. The finger and wrist flexor tendons also pass through the tunnel. The median nerve connects impulses from the brain to the arm, thumb, first two fingers, and half of the ring finger and controls many muscles of the hand, wrist, and forearm.

What causes it?

Figure 1

Carpal Tunnel Symndrome occurs when the median nerve is squeezed as it passes through a narrow tunnel of bone and ligament in the palm area of your hand.

Any increase in fluid pressure within the narrow compartment can compress the median nerve. Repeated up and down movements at the wrist and fingers, especially combined with gripping, can irritate the structures in the tunnel and cause swelling. Other causes such as pregnancy, diabetes, and thyroid disorders can create fluid retention and lead to median nerve compression.

What are the warning signs?

pins and needles sensations in the fingers

pain and soreness in the wrist and hand that may wake you at night

weakness in grip and clumsiness handling objects

Tendinitis and tenosynovitis

What is it?

Tendons attach muscle to the bone. Microscopic tears in a tendon can occur if the tendon is overused, leading to inflammation of the tendon, or tendinitis. Once injury occurs, the body produces scar tissue in order to heal the area of trauma. The injured tissue is often thicker and painful to the touch. Each time the muscle is used, it pulls at the injured tendon, causing more pain and more scar tissue formation. The chemicals that cause the swelling can irritate the tendon further.

Many tendons in the wrist and hand are enclosed in sheaths with lubricant that protects them (similar to the pistons firing in the engine of a car). If the tendon and the sheath rub and develop too much friction, irritation, overproduction of fluid, and swelling result. This is called tenosynovitis.

Common upper extremity tendinitis

DeQuervain's disease is tenosynovitis at the base of the thumb and wrist where 2 tendons meet. Pain can be felt with movement of the thumb, such as hitting the space bar on a computer keyboard with an outstretched thumb and activities with increased pinch force.

Trigger finger/thumb occurs when swelling forms a nodule on the finger flexor tendon at the distal palm. The tendon cannot slide within the "pulley system," which causes a "snap" with movement of the finger.

Lateral epicondylitis (tennis elbow) is inflammation of the common extensor tendon which attaches on the outside of the elbow. The tendon connects to the muscles used to straighten the fingers and bend the wrist backwards. Pain can be felt on the outside of the elbow and can radiate down the forearm. Repeated reaching or excessive mouse use can cause this problem. (You don't have to play tennis to develop this problem!)

Medial epicondylitis (golfer's elbow) is inflammation of the common flexor tendon which attaches to the inside of your elbow. This is similar to tennis elbow but is less common. This affects the muscles used to bend the fingers and wrist. Pain can be felt on the inside of the elbow.

Shoulder
impingement, rotator cuff tendinitis, and biceps tendinitis

These all can occur as a result of the same problems and can become a "vicious cycle." Causes such as using a mouse repetitively with an outstretched arm, slouching, and weak shoulder and upper back muscles can irritate the shoulder tendons. When a tendon becomes irritated and swollen, it can get pinched between the bony structures of the shoulder joint. This is called impingement.

The 2 most common structures that become "pinched" are the biceps and rotator cuff tendons. Pain can be felt in the shoulder when lifting the arm forward or out to the side. Weakness results from disuse and pain inhibits proper muscle function. Weakness of the shoulder muscles causes impingement to worsen, due to muscle imbalance, and impingement causes further pain and swelling in the tendon.

Neck
and back pain

Figure 2

Your lumbar curve, which bears the most of the strain of sitting, needs constant support.

The
natural curves of the spine should be maintained as much as possible
throughout daily activities to avoid unnecessary wear and tear on
the spine. The spine consists of 7 neck (cervical) vertebrae, 12
upper and mid back (thoracic) vertebrae, and 5 low back (lumbar)
vertebrae that enclose and protect the spinal cord (Figure 2). Between
the vertebrae are the discs, the shock absorbers of the spine. Ligaments
connect the vertebrae and provide stability, but are non-elastic.
The muscles attaching to the spine control spine movement and are
elastic. Nerves branch off the spinal cord at each vertebral level
and travel from the neck to the arms and from the low back to the
legs. Also at each vertebral level are facet joints, one on each
side, connecting adjacent vertebrae to one another. The facet joints
create movement in the spine, much like other joints in the body.

Certain structures in the spine are more "forgiving" than others to injury. Muscles are elastic and heal quickly if injured. Discs, joints, and ligaments are not elastic. They take much longer to heal and don't recover their strength as well when injured, leaving a person more susceptible to reinjury. Nerves have some elastic properties but are extremely sensitive and take a very long time to heal.

Using improper posture and body mechanics make muscles work harder and puts undesirable forces on the discs, joints, and ligaments. Once the muscles supporting the spine fatigue, the discs, nerves, and joints become more vulnerable to injury.